The Guardian Amp will run out, we also don't know if it will amp rulk like it did SBP.
Ill accept that rulk can remove the guardian amp but I don't think he can drain SBP and leave him powerless. I think you guys are forgetting that sunlight affects sbp's powers differently than superman's. All SBP needed was rays of sunlight hitting his fingertips to get back to full strength. How much are those rays of sunshine going to amp rulk? Not a lot.
SBP wins.